BIOL4260 Study Guide - Midterm Guide: Qt Interval, Pr Interval, Stethoscope
Document Summary
Chapter 22: heart conduction system and cardiac cycle. Electrical events of the heart: heart depolarizes and contracts without nervous system stimulation, although rhythm can be altered by the. Setting the basic rhythm: the intrinsic conduction system: coordinated heartbeat is a function of, presence of gap junctions, intrinsic cardiac conduction system, network of non-contractile (autorhythmic) cells. Subendocardial conducting network (purkinje fibers: 1) sinoatrial node- pacemaker of heart in right atrial wall, depolarizes faster than the rest of the myocardium, generates impulses about 75x per minute (sinus rhythm) Inherent rate of 100x per minute tempered by intrinsic factors. Impulse spread across atria, and av node: 2) av node- in inferior interatrial septum, delays approximately 0. 1 second, because fibers are smaller in diameter, have fewer gap junctions, allows atrial contraction before ventricular contraction. Inherent rate of 50 x per minute in absence of sa node input: 3) av bundle (bundle of his)
